Jennifer Marohasy

a forum for the discussion of issues concerning the natural environment

Archives for September 2017

Faux Record Hot Days, Including at Mildura

By

Alan Jones AO
Radio 2GB, Sydney

Dear Alan,

This spring has begun with the Bureau of Meteorology announcing a new ‘hottest September day on record’ almost every other day.

Last Saturday, for example, we heard that it was the hottest September day in Mildura since 1889. Really? Hotter than 1905 or even 1938 – those were hot years in Mildura.

Extreme heat in inland Australia is usually associated with prolonged drought. But this year there is water in the Murray River; further, modern Mildura is generally considered up to half a degree cooler on average than before the widespread development of irrigation – back in the 1930 and 1940s, for example, drought really was the norm, along with rabbit plagues and dust storms.

Before the advent of irrigation the Murray river would run dry during periods of extended drought. These were exceptionally hot years in the Murray Darling Basin, and include 1915 and 1941. Photograph taken by Jennifer Marohasy, upstream of Mildura some years ago – in about 2007, which was a drought year post the building of the Hume Dam.

I wrote to Minister Josh Frydenberg earlier in the week explaining that these new record hot days are unlikely to withstand scrutiny – for Mildura or anywhere else. My letter included a fair amount of technical detail, and a request for data to enable a direct comparison of temperature measurements from the old-style mercury thermometers with the new style electronic probes in automatic weather stations (AWS) – letter attached.

In the case of Mildura, the current AWS electronic probe was installed on 27th June 2012 – the last official measurement from a mercury thermometer at Mildura was actually on 31st October 1996. Assuming a time constant of 18 seconds for the current probe and given the Bureau’s current method of only taking one-second readings (i.e. taking spot readings – rather than averaging over at least one minute in accordance with World Meteorological guidelines), then the recent record hot day for Mildura is probably only comparable to measurements taken back to September 2012 (last 5 years), perhaps back to 1996 (last 21 years) – certainly not back to 1889 as claimed by the Bureau and reported in The Age.

Minister Frydenberg has been kind enough to acknowledge receipt of my letter, but he doesn’t seem to get how important sorting out the mess that is the Bureau of Meteorology actually is. He has suggested that we meet in a few weeks, when he is not so busy as he is at the moment. Of course, Ministers are always busy – what gets done depends on what they choose to make a priority.

I am writing to you now because you have been so effective in the past at getting some things done. For example, after you interviewed me on Wednesday 26 July about the Thredbo weather station and the artificial limits the Bureau had imposed on the measurement of cold temperatures: the very next day – after 10 long years of the imposition of these limits – they were lifted at Thredbo.

Perhaps, you could invite me back onto your program to discuss this issue of faux hot day records?

This is the first time I have actually requested to come on your program. As those close to me know, I usually don’t sleep the night before such a radio or television interview – because I find it all so frightening. I much prefer to analyse data alone, write technical papers with colleagues, and go canoeing with just nature.

Perhaps just writing this letter to you, and posting it at my blog with be enough?

You could perhaps interview Craig Kelly MP instead – because he is across this issue. I see that Steve Price has been standing-in for you recently: perhaps Steve Price could interview Craig Kelly MP? You/Steve Price would really only need me if someone from the Bureau was prepared to actually come-on your show – then I would be keen to come-on and we could have a proper discussion about the myriad of technical issues that need sorting. In the meantime, there really is a need for a few more people to start discussing these issues in general terms – then the Minister might realise, finally, that there is no need for the average Australian to be paying ever more for their electricity because we may not actually have run-away global warming.

For me the overriding issue is the integrity of the historical temperature dataset, specifically the Australian Data Archive for Meteorology (ADAM). Indeed, I am currently driving my work colleagues mad-with incessant complaints about no-longer being able to trust any of the data from the Bureau of Meteorology.

Previously, I’ve complained about the remodelling by the Bureau of the ACORN-SAT dataset, while working with data from ADAM for my rainfall forecasting. But since discovering the limits on the recording of cold temperatures, and then coincident to this that the Bureau are taking spot-readings rather than averaging – it all seems more desperate than ever.

Yours sincerely
Dr Jennifer Marohasy
Noosa, Qld

Copy:
Craig Kelly MP
Steve Price (via Carla Horton)
John Roskam, IPA

Attachment/letter to Minister Frydenberg: https://jennifermarohasy.com.dev.internet-thinking.com.au/wp-content/uploads/2017/09/Marohasy-ABC-4-Mildura.pdf

Bureau Management Rewrites the Rules – Again

By

Following is the latest advice from the Australian Bureau of Meteorology regarding measurement of temperatures from automatic weather stations (AWS). This advice contains numerous errors of fact and is inconsistent with the information in an internal review issued just last Thursday.

The following misinformation has just been posted at the official Bureau website:
http://www.bom.gov.au/inside/AWS_Review_Fast_Facts.pdf

My responses to the inaccuracies in this document are prefaced with JM, and inserted herein.

FAST FACTS: How does the Bureau measure temperature?

1. The Bureau measures air temperature using an electronic sensor (a platinum resistance thermistor) placed within a Stevenson Screen, and temperature is recorded every second.

JM: No. The temperature is measured every second, it is not recorded every second by the Bureau. Rather, the Bureau has explicitly stated, most recently in an internal report released just last Thursday, that for each one minute temperature it only records the highest one-second temperature, the lowest one-second temperature, and the last one-second temperature – in that one minute interval. The Bureau does not record every one-second value. In the UK, consistent with World Meteorological Organisation Guidelines, the average temperature for each minute is recorded.

2. The air temperature fluctuates frequently on the scale of seconds. By using a sensor which has a longer response time than the fluctuations of the air temperature, the sensor “averages” these fluctuations.

JM: No. Electronic sensors have shorter response times than mercury thermometers. So, to ensure there is no discontinuity in measurements when the transition occurred from mercury thermometers to electronic probes the maximum and minimum values need to be calculated from one-second readings that have been averaged over at least one minute.

3. Both the mercury-in-glass thermometers, and the electronic sensors, are housed within a Stevenson Screen. The time taken for air to be exchanged from the outside environment to within the screen provides a further time integration for the measurement of the ambient air temperature.

JM: Noted.

4. The response time of the sensor used in the Bureau AWSs is as long or longer than the changes in the temperature of the air it is measuring.

JM: This may be the case. But the key issue has always been achieving consistency with measurements from the mercury thermometers – so there are no discontinuities in the temperature record with the transition from mercury thermometers to temperature probes. There was a report issued by the World Meteorological Organisation (WMO) in 1997 entitled ‘Instruments and Observing Methods’ (Report No. 65) that explained because the modern electronic probes being installed across Australia reacted more quickly to second by second temperature changes, measurements from these devices need to be averaged over a one to ten-minute period to provide some measure of comparability with the original thermometers.

5. This means that each one second temperature value is not an instantaneous measurement of the air temperature but an average of the previous 40 to 80 seconds. This process is comparable to the observation process of an observer using a “mercury-in-glass” thermometer. Are these methods consistent with international best practice?

JM: The two claims made in this dot point are not consistent with published studies. As regards ‘these methods’, if this is an attempt at justifying an instantaneous one-second reading, then the answer is: No. .

[Please also note the information as a postscript from Lance Pidgeon – scroll down to after the photograph of us both at Goulburn.]

6. The Bureau’s procedures comply with the World Meteorological Organization’s Guide to Meteorological Instruments and Methods of Observation (the CIMO Guide) WMO-No. 8 (2014 edition). The guide is available here.

JM: The guide at the said link clearly states on page 540 (Part 2, Section 1.3.2.4) that atmospheric air temperature be reported as 1 to 10 minute averages. Therefore, the Bureau’s procedures are not compliant with WMO guidelines.

7. The guide recommends that temperatures be integrated over time to smooth out rapid fluctuations. There is more than one method of achieving this. The WMO guidelines do not prescribe which method to take. In its automatic weather stations the Bureau achieves this by using platinum resistance thermometers. These are comparable to mercury in glass thermometers.

JM: No. The guide clearly states that readings from platinum resistance thermometers are not comparable with instant one-second readings from mercury in glass thermometers.

In summary, given the Bureau is taking one-second extrema, rather than following its own published guidelines (Instruments and Observing Methods Report No. 65, WMO/TD No. 862) recordings taken by the Bureau over the last twenty years from automatic weather stations across Australia may not be fit for purpose. In particular, temperature measurements from Australia since at least 1990 have not been recorded consistent with calibration, and therefore are likely to be invalid?

Jennifer Marohasy
11 September 2017 – 9pm

This advice is also provided as a PDF here: FAST FACTS -Refuted-V2

Jennifer Marohasy and Lance Pidgeon at the Goulburn AWS in early August 2017. Photograph courtesy of The Australian newspaper.

Comment from Lance follows as an important postscript

Following the link provided in the ‘Fast Facts’, I found this:

“It is recommended that the time constant, defined as the time required by the thermometer to register 63.2% of a step change in air temperature, should be 20 s. The time constant depends on the airflow over the sensor.”

This is a completely different thing to the sampling rate and averaging. It is describing the conditions BEFORE the one second sample rate not after.

This time, specifies the curve which is not an average. To compare an exponential decay curve to an average is wrong. If the curve time was over 60 seconds then the most recent would have most of the influence while the oldest would only have the influence of three timeconstants (63 percent of 63 percent of 63 percent).

A rule of thumb is that about 5 time constants need to pass before a reasonable measurement can be taken and 7 or more for an accurate measurment.

So is the BoM also trying to hide that this (before the averaging) time constant is also too short by confusing 5, 7 and 1 time constants as “40 to 80”?

Also, I just noticed that the standard calibration method looks to remove and ignore the noise during the procedure. In particular:

“Since the measurement instrument is an integral part of the electrical thermometer, its calibration may be checked by substituting the resistance thermometer by an accurate decade resistance box and by applying resistances equivalent to fixed 5 K temperature increments over the operational temperature range. The error at any point should not exceed 0.1 K. This work would normally be performed by a servicing technician.”

And with reference again to the ‘Fast Facts’, it is sad that the Bureau do not appear to understand the difference between a thermistor and a platinum resistance thermometer. I write this because the document that Jennifer has posted begins with reference to a ‘thermistor’ and ends with comment about a ‘platinum resistance thermometer’.

Lance Pidgeon
via Crookwell, near Goulburn
12 September 2017 – 8am

*****

As far as I can tell the 2014 document Lance quotes from (which the Bureau claim they are working in accordance with – though clearly they are not) is a someone garbled version of a technically solid report published in 1997, which includes the following advice:

An extract from ‘Instruments and Observing Methods Report No. 65, WMO/TD No. 862’

*****

According to the ‘Fast Facts’, the Bureau’s procedures comply with the World Meteorological Organization’s Guide to Meteorological Instruments and Methods of Observation (the CIMO Guide) WMO-No. 8 (2014 edition). Following are two important extracts from this document:

Uploaded by Jennifer on 14 September 2017 – for future reference.

John has Plus 10 Degrees, Bureau Loses Minus 10 Degrees

By

He studied chemistry at Imperial College, London, has 10 degrees, including a law degree, and has published more than 100 scientific papers. I’m referring to my husband, John Abbot. He is also a man of few words.

John Abbot standing in front of the Noosa River, Queensland – not far from the Climate Lab where he works on rainfall forecasting using artificial neural networks.

Last Friday morning, after flipping through the Australian Bureau of Meteorology’s latest 77-page internal report – Review of the Bureau of Meteorology’s Automatic Weather Stations – he looked up at me, and then said, “But this is all about you.”

The report begins by explaining that the Bureau has 695 automatic weather stations spread across Australia, and that data from this network underpins all of the services the Bureau delivers, enabling more than 500,000 public forecasts, and nearly 15,000 weather and ocean warnings which are issued each year. The report then goes on to explain that just two of these weather stations are “not fit for purpose” – Goulburn Airport (Goulburn) and Thredbo Top Station (Thredbo).

On the 5th and 18th July, respectively, I explained in detail at my blog that after temperatures below minus 10 degrees Celsius were measured by the Goulburn and Thredbo weather stations they were not subsequently recorded as such in the appropriate database by the Bureau.

While the Bureau strenuously denied it was setting limits on how cold a temperature could be recorded from any particular weather station, the Minister Josh Frydenberg nevertheless insisted on the review – and of the entire AWS network.

The Minister phoned me late on Thursday, to let me know that the review was done and that the investigation found that Goulburn and Thredbo were the only stations, out of the entire network, where temperature records had been affected.

What are the chances? Of the nearly 700 weather stations, I stumbled across the only two with problems!

Goulburn was discovered because my friend Lance Pidgeon lives nearby. He was up early on the morning of 2 July concerned his pipes were going to freeze and burst – while watching the live AWS temperature readings tick-over for that weather station. He then texted me when what appeared to be a new record for July of minus 10.4 was reached, only for us to both see this rounded-up to minus 10.0.

Thredbo was discovered because, after making a fuss about Goulburn, I wanted to check that the Bureau had actually lifted the limits on readings below minus 10. So, two weeks later I decided to get up early and watch for the lowest second-readings at one of the stations in the snowfields. Given the weather set-up that morning, I thought it might be cold across that region. Why did I choose Thredbo – of all the weather stations in the Australian Alps? Simply because my school friend Diane Ainsworth died in the landslide there twenty years ago.

“And I’m vindicated in that 77-page report,” I said to John Abbot – last Friday morning.

But unfortunately, neither the report, nor its recommendations are going to fix the more substantive issues that I have been raising since at least 2011 – when much of the city of Brisbane was flooded by emergency releases from a dam that was never meant to ever fill again, according to the best guesses from our Bureau.

Indeed, in the years preceding the flooding of Brisbane the Bureau’s own David Jones, Head of Climate Analysis, was often penning opinion pieces, including for the Sydney Morning Herald, that explained drought was the new norm for Australia. In an email, back in September 2007 he went as far as to say that: “climate change here in Australia is now running so rampant that we don’t need meteorological data to see it.”

Dr Jones could be characterised as a ‘true believer’. He is now the Head of Climate Monitoring and Prediction at the Bureau. Perhaps not surprisingly the Bureau keeps telling us that next year will be hotter than the last and that this last winter was the warmest on record – never mind the record number of frosts being tallied up by farmers across the south east.

For some years every minister responsible for the Bureau has successfully staved-off what must come eventually: a proper public review into the operations of this institution, which has lost its way. For some years, ministers responsible for the Bureau have been claiming that there can be no external review because there is a need to maintain public confidence – they seem to know that a transparent review and public confidence are incompatible.

The report pertaining to this latest internal review claims that even though there has been a strict limit on how cold temperatures could actually be recorded at Thredbo, Australia’s climate history has in no way been compromised. This is nonsense!

Since the year the new automatic weather station was installed at Thredbo – by coincidence the year my friend Diane died in the landslide – there has been a significant reduction in the number of days measuring minus 10 degrees or lower.

To be clear, and contrary to what is written in this latest report from the internal review, the equipment installed at Thredbo back in 1997 is world class. There is nothing wrong with the equipment, and it can record temperatures down to minus 60 degrees Celsius.

The problem is senior management at the Bureau, and specifically their instructions for how the equipment is to be operated.

For example, and to raise another issue: because the electronic probes in the new automatic weather stations are much more sensitive to temperature change than the previous liquid-in-glass thermometers, the one-second measurements from the new probes must be averaged over 1 to 10 minutes before taking a recording. This is detailed in various reports and is also World Meteorological Organisation policy. So, in the UK, the data loggers are set to automatically average over 1 minute; in the US, it is 5 minutes.

The Bureau has the correct documentation in place, with the key report – based on detailed experimental work undertaken here in Australia in the early 1990s – published back in 1997. But the Bureau is not actually following its own guidelines.

I have worked this out by comparing readings from different pages as displayed on the Bureau’s website. But according to the new internal review of AWS operations, this must stop. In particular, the review found, “the current data flow architecture creates situations where data can be delivered to, and displayed on, the Bureau’s website via multiple pathways and this can be potentially inconsistent and confusing for end users.”

I was initially confused but then treated the various anomalies from the perspective of a puzzle to be solved.

This new report does clarify many issues. Indeed, while I initially thought that the new limit of -10.0 degrees Celsius had just been put in place this winter – it is apparent from the report that it has been in place at Thredbo for ten years, since 2007. What is not clear is how a value that is measured below minus 10 by the equipment is actually recorded, with my observations suggesting that at Thredbo it ends up as blank, while at Goulburn it is rounded to minus 10.0.

Thredbo is not far from the peak of Australia’s highest mountain, Mt Kosciusko. Temperatures have been recorded at Thredbo since January 1966. On six separate days in 1968 temperatures dropped to -10 or below. On 23rd June 1968 temperatures dropped to -11.6. On 28th, 29th and 30th July of that year temperatures of -10.3, -10.6 and -10.1 were recorded. On 28 July 1980, a record low minus 14.7 was recorded. In July 1994, which was an exceptionally cold winter, minus 13.6 was recorded. Not far from Thredbo, at Charlotte Pass in June 1994, the all-time lowest minimum in Australia of minus 23 degrees Celsius was recorded.

During June and July of this year, blizzard conditions were experienced across the Australian Alps, but we will never know how cold it actually got. Because a MSI1 card reader prevented the equipment – able to record down to minus 60 – from recording below minus 10 at Thredbo and probably also at many other locations. It is also impossible to know how cold this last winter was relative to 1994 because the weather station at Charlotte Pass was closed in March 2015 – it is no longer in operation.

Earlier this year, specifically on Wednesday 26 July, I was interviewed by Alan Jones on radio 2GB. He has one of the highest rating talkback radio programs in Australia. From about 7.40 a.m. that morning we discussed my concerns, specifically about limits on how cold temperatures can be recorded at Thredbo.

According to the new internal report from the Bureau, and apparently by coincidence, the very next day, on 27 July the limits were lifted at Thredbo. After 10 years at least, the Thredbo weather station was able to record very low temperatures again.

‘Low’and behold: on 2 August, a minimum temperature of -10.9 was recorded at Thredbo.

It had been such a long time since such a cold temperature had been recorded at Thredbo – at least 15 years coincident with the installation of the card that prevented the measurement of temperatures below minus 10.4.

Rather than announce the lifting of the ban on very cold temperatures at Thredbo, that very same day, 2 August 2017, the Bureau announced that July 2017 had been the warmest on record – ever, for Australia.

Contrary to the Minister’s press release of last Thursday, core issues at the Thredbo weather station have not been fixed – and these are issues that also affect the other 694 weather stations. By its own admission in the report (page 22), the Bureau is recording one-second extrema from at all weather stations: it is not averaging these values over at least one minute as is standard practice in the UK, or over 5 minutes as is done in the US.

Recording one-second extrema (rather than averaging) will bias the minima downwards, and the maxima upwards. Except that the Bureau has been placing limits on how cold an individual weather station can record a temperature, so most of the bias will have been upwards over the last few years – in accordance with Dr Jones’ favourite story about man-made warming.

It is well and truly time for an open, transparent and independent external review of the Bureau, and its management.

And John Abbot would prefer that it wasn’t just about me. So, such a review would need to address the multitude of other issues that have been documented over the years including by Warwick Hughes, Ken Stewart, Joanne Nova, Maurice Newman and indeed also by John Abbot – most recently in the journal Atmospheric Research (volume 197, page 290) where he explains that the Bureau’s probabilistic seasonal rainfall forecasts are misleading.

****
A version of this article was first published at The Spectator Australia.

Vindicated: Bureau not following WMO guidelines

By

TWO decades ago the Australian Bureau of Meteorology replaced most of the manually-read mercury thermometers in its weather stations with electronic probes that could be read automatically – so since at least 1997 most of the temperature data has been collected by automatic weather stations (AWS).

Before this happened there was extensive testing of the probes – parallel studies at multiple site to ensure that measurements from the new weather stations tallied with measurements from the old liquid-in-glass thermometers.

There was even a report issued by the World Meteorological Organisation (WMO) in 1997 entitled ‘Instruments and Observing Methods’ (Report No. 65) that explained because the modern electronic probes being installed across Australia reacted more quickly to second by second temperature changes, measurements from these devices need to be averaged over a one to ten-minute period to provide some measure of comparability with the original thermometers.

This report has a 2014 edition, which the Bureau now claim to be operating under – these WMO guidelines can be downloaded here:
http://www.wmo.int/pages/prog/www/IMOP/CIMO-Guide.html .

Further, section 1.3.2.4 of Part 2 explains how natural small-scale variability of the atmosphere, and the short time-constant of the electronic probes makes averaging most desirable…  and goes on to suggest averaging over a period of 1 to 10 minutes.

I am labouring this point.

So, to ensure there is no discontinuity in measurements with the transition from thermometers to electronic probes in automatic weather stations the maximum and minimum values need to be calculated from one-second readings that have been averaged over at least one minute.

Yet, in a report published just yesterday the Bureau acknowledge what I have been explaining in blog posts for some weeks, and Ken Stewart since February: that the Bureau is not following these guidelines.

In the new report, the Bureau admits on page 22 that:

* the maximum temperature is recorded as the highest one-second temperature value in each minute interval,

*the minimum is the the lowest one-second value in the minute interval, and

* it also records the last one-second temperature value in the minute interval.

No averaging here!

Rather than averaging temperatures over one or ten minutes in accordance with WMO guidelines, the Bureau is entering one second extrema.

The value of minus 10.4 marked with a red asterisk is the lowest one second measurement for the previous 60 seconds… to 6.17am on 2 July 2017 at Goulburn airport. This one second reading was initially rounded-up up to -10.0, but after some protesting was recorded in the ADAM database as the minimum for Goulburn airport for that day – and a new record for July of minus 10.4.

Recording one-second extrema (rather than averaging) will bias the minima downwards, and the maxima upwards. Except that the Bureau is placing limits on how cold an individual weather station can record a temperature, so most of the bias is going to be upwards.

****

The Bureau’s new review can be downloaded here: http://www.bom.gov.au/inside/Review_of_Bureau_of_Meteorology_Automatic_Weather_Stations.pdf

I’ve also posted on this report, and limits on low temperatures, here: https://jennifermarohasy.com.dev.internet-thinking.com.au/2017/09/vindicated-bureau-acknowledges-limits-set-cold-temperatures-can-recorded/

Vindicated: Bureau acknowledges limits set on how cold temperatures can be recorded

By

THE Bureau has a network of 695 automatic weather stations (AWS) across Australia. In a report released late yesterday it acknowledged issues with the performance of just two of these: Goulburn Airport (Goulburn) and Thredbo Top Station (Thredbo). These are the same two weather stations that I reported at my blog were not recording temperatures measured below minus 10 degrees on the 5th and 18th July, respectively.

While the Bureau strenuously denied it was setting limits, the Minister Josh Frydenberg nevertheless insisted on a review of the entire AWS network.

The Minister phoned me late yesterday to let me know that the report had just been published, and that the Bureau’s investigations confirmed that Goulburn and Thredbo were the only sites where temperature records had been affected by the inability of some Bureau AWS to read low temperatures.

What are the chances? Of the nearly 700 weather stations, I stumbled across the only two with problems.

Goulburn was discovered because my friend Lance Pidgeon lives nearby and was up early on the morning of 2 July concerned his pipes were going to freeze and burst – while watching the live AWS temperature readings tick-over on that weather station, then letting me know when the record for July of minus 10.4 was reached: only to see it rounded up to minus 10.0.

Thredbo was discovered because, after making a fuss about Goulburn, I wanted to check that the Bureau had actually lifted the limits on readings below minus 10. So, two weeks later I decided to get up early and watch the one-second reading at one of the stations in the snow fields on the Sunday morning of 16th July thinking it might be a cold morning. Why did I choose Thredbo – of all the weather stations in the Australian Alps? Simply because my school friend Diane Ainsworth died in the landslide there twenty years ago.

Never mind – I’m vindicated!

The Bureau has now acknowledged that it had inadvertently set limits on how cold temperatures could be recorded at Goulburn and Thredbo.

To be clear the equipment has a general operating range to minus 60 degrees Celsius, but smart card readers – with a nominal range to only minus 10 degrees Celsius and that stop reading all together at minus 10.4 – were inserted placing limits on the actual recordings, not the measurements.

According to the report published late yesterday, the cards were inserted into the Goulburn weather station in September 2002, and into the Thredbo weather station in May 2007. So, for a period of nearly 15 years there has been a limit on how cold temperatures can be recorded at Goulburn, and for nearly 10 years at Thredbo.

This Goulburn weather station was first opened in 1990, and had previously recorded temperatures below minus 10 degrees Celsius in 1994,1999 and 2000 – with a record cold minus 10.9 recorded on 17 August 1994.

The Thredbo weather station opened in 1966, and recorded an average of 2.5 days per year below minus 10 degrees until 1996 when an automatic weather station was installed – replacing the previous liquid-in-glass manually-read thermometers.

Since the AWS was first installed, back in April 1997 there has been a reduction in the average number of days per year when temperatures have fallen below minus 10 degrees Celsius, as shown in the chart.

Further, since May 2007 when the MSI2 sensor interface card was replaced with the MSI1 card (see page 50 of the new report from the Bureau) there has been no potential to record below minus 10.4. Yet not far from this location, at Charlotte Pass, an all-time record low temperature of minus 23 degree Celsius was recorded on 29 June 1994; this was with an old style liquid-in-glass thermometer – not with an AWS.

How can this review possibly conclude that there are no problems with the other 693 automatic weather stations – and there has been no impact on official temperature records from the limits it now acknowledges were placed on recordings from Thredbo and Goulburn?

Surely, there is now evidence enough for a proper external review to be initiated, this should be a Parliamentary Enquiry, through the House Energy and Environment Committee.

The Bureau’s report can be downloaded here: www.bom.gov.au/inside/Review_of_Bureau_of_Meteorology_Automatic_Weather_Stations.pdf

Are Recordings from Electronic Devices Comparable – or Not?

By

Because a change in equipment can potentially create discontinuities in a temperature record, it is Australian Bureau of Meteorology policy to have new equipment recording side-by-side with old equipment for a period of at least 2 years. In this way, readings from the new equipment can be compared with readings from the old equipment, including to check they are comparable – that there are no discontinuities.

Since the 1990s, the Bureau has been converting from manually read liquid-in-glass thermometers (e.g. mercury thermometers) to automatic weather stations with electronic probes.

At Wilsons Promontory lighthouse the change was made on 18th September 2000.

The electronic probes and liquid-in-glass thermometers are housed in the white box (the Stevenson screen) in the foreground of this picture of Wilsons Promontory lighthouse. It is unfortunate that solar panels have been installed such that they are facing the box with the thermometers – I have complained about this in previous correspondence. This photograph was taken by Daynaa (daynaa2000.wordpress.com) with permission to republished requested in 2015.

As part of an ongoing investigation into Australia’s temperature history, I requested the comparative data – the temperature recordings for Wilsons Promontory lighthouse from the electronic device and also from the original thermometers, which were installed back in 1872. The Bureau has never provided me with this information despite repeated requests, since at least August 2015 – as per the following email (Appendix 1).

I have since published a technical paper assessing the quality of the maximum temperature series from Wilsons Promontory – assuming the data from the electronic probe is comparable with the thermometers. This research is detailed in the international peer-reviewed journal Atmospheric Research, Volume 166.

In a recent blog post, however, I suggest that temperature recordings from automatic weather stations (i.e. from the electronic devices) are not comparable because the Bureau is recording one second extrema rather than averaging measurements over one minute. It is important to average the readings from the electronic probes over at least a minute because the mercury thermometers respond more slowly to temperature change.

In order to help clarify whether or not the recording from the electronic devices are comparable, I am again requesting that the data for Wilsons Promontory lighthouse be made available. In particular, I would like the daily maximum and minimum temperature values from the liquid-in-glass thermometers from 1872 to the present, and the one second readings since September 2000 to the present. Towards this end, I have just sent an email to Dr David Jones, who is the ‘Head of Climate Analysis’ at the Bureau. This email also follows (Appendix 2).

*****

APPENDIX 1

———- Forwarded message ———-
From: Jennifer Marohasy 
Date: Tue, Aug 25, 2015 at 2:48 PM
Subject: seeking clarification and additional data
To: climatedata@bom.gov.au

Hi,

I’m seeking clarification regarding equipment used to measure surface air temperatures at Wilsons Promontory lighthouse, Bureau number 85096.

I understand that both alcohol and mercury thermometers were used to measure minimum and maximum temperatures from November 1872 until September 2000.

I understand that the alcohol thermometers were removed and replaced with a temperature probe on 18th September 2000.

I understand that since 18th September 2000 both a temperature probe, and also the original mercury thermometer have been used to measure temperatures at Wilsons Promontory.

I understand that a second mercury thermometer was installed at Wilsons Promontory on 16th December 2002.

Could you please confirm that this assessment is correct?

Could you please also provide me with the complete digital/electronic temperature record (maximum and minimum) as measured from each of these different thermometers for the period of their available record.

I am particularly keen to know if there is a single continuous monthly record for the mercury thermometer installed in 1872, to the present.

Could you please also clarify which thermometer was used to supply the maximum and minimum values available online, i.e. at http://www.bom.gov.au/climate/data/

Kind regards

Jennifer Marohasy
Tel. 041 887 3 222

******
APPENDIX 2.

Jennifer Marohasy
1:09 PM (4 minutes ago)

to David, Craig, William, climatedata,

Hi David

I am writing to you as the head of the Climate Analysis Section at the Bureau. Also, I understand you were the author of a 1997 report published by the World Meteorological Organisation (WMO) emphasising the need to average measurements from electronic temperature probes over one minute: in order for these measurements to be comparable with measurements from the previous liquid-in-glass thermometers (e.g. mercury thermometers).

The link to this report is here: https://library.wmo.int/pmb_ged/wmo-td_862.pdf

Having watched how temperatures are recorded by electronic probes at automatic weather stations over the last three months, I am concerned that the policy detailed in this report is not being followed. My observations are consistent with advice from David Barlow in your Sydney Office: in particular that only one second extrema are being recorded.

It is now over two years since I requested data to make the comparisons myself between temperatures as measured and recorded at automatic weather stations with temperatures as measured and recorded in the old liquid-in-glass thermometers. Specifically, I sent an email requesting the AWS (electronic probe) and also thermometer data for Wilsons Promontory lighthouse back in August 2015, and then followed-up on this first by email, and then by phone in October 2015 (see following).

Could this data now be provided as a matter of urgency. As per my most recent blog post I would like:

“the daily maximum and minimum temperature values from the liquid-in-glass thermometers from 1872 to the present, and the one second readings from the electronic probe (AWS) since September 2000 to the present.”

I understand that before the move to electronic recordings, there was extensive testing of the electronic devices – parallel studies at multiple site to ensure that measurements from the new AWS weather stations tallied with measurements from the old liquid-in-glass thermometers in the Stevenson screens.

Could the internal reports from this experimental work please also be made available as a matter of urgency. I have been unable to find any published studies.

Bill Kininmonth, who had your position within the Bureau from 1986 to 1998, has assured me by telephone that all the experimental work was done. Bill is also of the opinion that measurements are averaged over 10 minutes, if not one minute intervals.

Could it be that after Bill’s retirement in 1998, the policy was changed from averaging over 1 to 10 minutes to the simple recording of one second extrema? I can not, however, find any documentation for this. Also, this would be in contravention of WMO guidelines.

Long temperature series without discontinuities are critical to my work forecasting rainfall using artificial neural networks – a form of machine learning.

I am copying this email to Craig Kelly MP, as he is particularly interested in this issue, and also Bill Kininmonth.

The two blog posts that I refer to, with more information on the issues I raise are here:

Two Decades of Temperature Data from Australia – Not Fit for Purpose

Two Decades of Temperature Data from Australia – Not Fit for Purpose

Kind regards
Jennifer Marohasy
Tel 041 887 32 22

On Thu, Oct 8, 2015 at 10:13 PM, Jennifer Marohasy wrote:
Hi, I received notification that this email would be answered within 5 working days. It is now over one month. Could I please receive this information? Kind regards, Jennifer Tel. 041 887 32 22